Pneumatically controlled streams of chemicals are commonly used in the chemical industry, typically in the manufacture of polyurethane foams and the like. U.S. Pat. No. 4,129,636 is noted to disclose a process and an apparatus for filling a mold cavity with foamable reaction mixture of chemical components. The associated piston is said to be driven pneumatically, hydraulically, mechanically or electromagnetically. In U.S. Pat. No. 4,313,909 there is disclosed a method and an apparatus for the production of a reaction mixture for forming solid substances from flowable reactants. A device for producing a solid-forming or foaming flowable reaction mixture is disclosed in U.S. Pat. No. 4,378,335. An attempt to use an air actuated mixhead in an adhesive application where the streams of the reactive components were introduced into a static mixer failed.
The present invention which comprise a hydraulically actuated mixhead overcomes the above mentioned disadvantages. The mixhead includes the means to control the recirculation, and thus the temperature of the components, and the velocity of each of the streams to achieve accurate stop-start cycles. The design of the dividing joint assures the separation of the individual streams up to the point of their introduction into the reaction zone of a static mixer.